Multiplex broadcast system



Aug 5, 1930. E.- R. TAYLOR 1,772,166

r MULTIPLEX BROADCAST SYSTEM Filed Aug. 17 1926 5 vSheets-Sheet l .maar

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w E :gy-M 7 INVENTOR EZ?. Taylor BY W Q A TTORNE Y Aug- 5, 1930 E. R. TAYLOR 1,772,166

MULT IPLEX BROADCAST SYSTEM.

Filed Aug. 1'7 1926 3 Sheets-'Sheet 2 IN VEN TOR im, @jmp A TTORNE 5 Sheets-Sheet 5 Aug. 5, 1930. E. R. TAYLOR MULTIPLEX BROADCAST SYSTEM Filed Aug. 17 1926 IN VEN TOR EJB. ZWW

A TTORNE Y Patented Aug. 5, 1930*. l

narran strains sereni* ori-"icsA EDMUND R. TAYLOR, OFNRW YORK, N. Y., AssrGNoR TOAMERICAN TELEPHONE AND TnLRGRAPi-r COMPANY, A CORPORATION or NEW YORK vIVIUIIZITIII?LEX BRCA1',CAST.1y SYSTEM Application led August 1'?, 1926.y rSerial No. 129,835.

This invention relates to multiplex broadcasting systems, and particularly to arrangements in such systems for interconnecting a plurality of sources of news, music or the like with a plurality of transmitting stations so that the programs originating at said sources may be simultaneously broadcast by said transmitting stations.

This invention results 'from long-continued experimentation with broadcasting systems. The iirst broadcasting system involved but one studio or program source and one transmitting station. These were permanently connected so that when the transmitting station was in operating condition all the sounds which were made in the studio were audible to the radio audience. This was soon found to be objectionable because certain sounds incidental to arranging the artists, etc., proved to be both disconcerting and displeasing. Accordingly a signal and control arrange- Ament was vevolved which disconnected the studio from the transmitting station when it was not desired that the sounds in the studio be heard by the radio audience. This kwas found to result in objectionable delays while one group of artists was leaving the studio and another was entering and preparing for the transmission of the next program. vAt a later time, this led to the provision of two or more adjacent studios so arranged'that while one group of artists was broadcasting another group of artistsr could be arranging themselves in another studio and preparing to broadcast.v

Almost from the beginning ot the period of experimentation it was i'eltv desirable to broadcast programs originating in one location simultaneously throughtwo or more vtransmitting stations. At any given time all of the' transmit-ting stations might be transmitting the same program, i. e., the program originating at one studio, and at other times various transmitting sta-tions might be transmitting different programs i. e., programs originating at dierent studios. At rst, this resulted in a rather complicated switching mechanismjbetween studios and transmitting' stations. The switching of studios and transmittingstations was accombroadcasting by one transmitting station of a program intended for another transmitting station, occasionally simultaneously with the proper program. The system described herein results from improvements made while experimenting with the old systems, and is designed to overcome the difculties of the old systems some of which are mentioned hereinabove. The present system is simple so that a non-technical man, such as an announcer, may operate it rapidly and smoothly.

Whereas the system is primarily designedv to interconnect a plurality of studios and a plurality of transmitting stations, it is equally applicable wheneved a-number of'sources of sound are to be connected'electrically to a number Vof other points. Obviously these points may be radio transmitters, public address systems, For the sake of convenience these will allv be referred to herein as transmitting stat-ions.

It will be understood that this system is particularly applicable Vwhere such connections must be made without appreciably Vchanging' the gain-frequency characteristics of the circuits involved. `In accordance with the present practice it 1s often desirable to operate several broadcasting studios inconnection with a numberof transmitting stations. The interconnecting system to accomplish this `is described herein merely for the sake of illustration, and is so arranged that may be connected to any one of the transmitting stations, no two ot the studios being connected to any one transmitting station at the same time. This is accomplished in a manner such that the audiences of the transwire broadcast systems, etc. n

any one of the studios mitting stations do not hear any of the switching noises and do not observe any appreciable delays between selections, or that any other program is being transmitted by any other transmitting station except the one the audiences are scheduled to receive.

It will be understood that one or more of the studios may be located in close proximity to the switching point and that one or more ofthe other studios may be located at a point or points widely remote therefrom and connected thereto by suitable signaling circuits, or by other transmission paths. It will be further understood that the studios, control room and transmitting stations shown herein may be'widely separated from each other and may be connected by any suitable medium or media, such as wire lines or radio circuits, within the scope ofthis invention.

While the nature of the invention will be pointed out with particularity in the appended claims the invention itself, both as to its objects and fea-tures, will be better understood from the detailed description hereinafter following when read in connection with the accompanyingvdrawing, in which Figures l, 2 and 3 schematically disclose the general principles of the invention, and in which Figs. 4 and 5, when placed side by side, show one application of the principles ot theinvention to a multiplex broadcasting system.

Referring to Fig. l, there are shown four studios, A to D, inclusive. The circuits from these studiosconverge in a control room CR, which may be, for example, adjacent to the studios. In this room the signals from the studios are amplilied and distributed to the various radio transmitters RT1 to. RT5, inclusive. The arrows .on the circuits between the studios A to D, the control room CR and the radio transmitters RT1 to RT5 indicate the direction of transmission of the program matter. Obviously the studios A tov D and the radio transmitters RT1 to RT5 may be adjacent to the control'room'CR and may be connected thereto by local or, perhaps, by long distance telephone lines or other transmitting media. Vl/Vhene'ver it becomes desirable to supplement a program originating at a studio With material originating at a remote point known as a pick-up point, such as a theater, the circuits from the remote pickupkpoint may be brought intothe control room CR and then into one of the studios, soV that the circuits 'may be controlled at that studio andappropriate announcements made whenever necessary by the announcer in that studio. These circuits from pick-up points have become known as nemo circuits, and they will be described in greater detail hereiiiafter.' Although the system hasbeen shown to include tour studios and five radio transmitters, it will be understood that the invention is not to be limited in that respect, butthat any number of studios may be con-` nected to any number ot radio transmitterslso that the programs from the various studios may be simultaneously broadcast by the various radio transmitters.

Fig. 2 shows three studios, A, B and C and the corresponding signaling circuits terminating in channel (horizontal) bus bars havf ing the amplifiers A1, A2 and A3 associated with these bus bars, respectively. These channel (horizontal) bus bars maybe con! studio associated therewith, and Vis furthery arranged so that no tWo channel (horizontal) bus bars may be connected to the same station (vertical) bus bar and the corresponding amplifier and transmitting station at the same time. In other words, the system is so ai'- ranged that any studio maybe connected to any transmitting station whenever thatr transmitting station is not already connected to l some other studio. Moreover, means (not shown) are provided so that the operating condition of any transmitting station is constantly indicated in the studios and in the .7

control room. Thus as soon as the program is finished in one studio the transmitting station may be connected to receive the program ot'lanother studio without anyappreciable loss of time.' v K In Fig. 2a number of dotted and undotted circles are shown to represent the `various relays, the dotted circlesv indicating operated f relays and the uiidotted circles indicating unoperated relays. In this particular arrangement the studio A is connected to the transmitting station TS1 throughthe corre-V sponding amplifier All. The studioB is connected to the transmitting stationsTSZ and TS6 through the corresponding amplifiers A1.2 and A16', respectively. VAnd studio C is connected to the transmitting station TS@ through the corresponding ampliiier A14. No studio is connected to the transmitting stations 'ISs and TSS. It is to be particularly noted that noone of thetransmitting stations TS1 to TSG, inclusive, is connected to more than one studio. Y In Fig. 3 the system is shown schematically in somewhat greater detail. In this figure only two studios A and are shown, rmerely for the sake of simplicity, and the studios may be connected to either one of two transmitting sie stations. In studio A there are shown, for

the sake ofsimplicity, onlytwo transmitters or microphones, one for the program and one' for the announcer, and control equipment CE1 for connecting the output of either ot' isc these transmitters to a control room ampliiier A, corresponding to studio A and its associated equipment. The studio control equipment will be described in greater detail in connection with Figs. 4 and 5. While the control room amplilier A has been shown as located at the control room this amplifier may, however, be located at the studio. This control room ampliiier A has a main relay MB1 associated therewith in order to place the output or' the control room amplifier A upon a channel bus bar CB1. There are also two line relays LR1 and LEZ, one corresponding to each transmitting station, so that the channel bus bar CB1, and hence the output of the control room amplifier A, may be connected to either of the transmitting stations. Moreover line amplifiers A21 and A22 are shown, each of these amplifiers corresponding to one of the transmitting stations. The line relays LR1 and LR2. are connected to the studio control equipment CE1 through the channels 21 and 22, respectively. By means ot these channels the output of the control room amplifier A, and consequently the output of studiovA, may be controlled through interlocking devices (not shown) so that the output of the control room amplii'ier A may be connected to either or both of the transmitting stations, if that transmitting station, or stations, is not connected to another studio, such as studio B. In other words, the interlocking devices (not shown) prevent the connection of more than one studio to one transmitting station at the same time. The control equipment in each studio may, of course, be located on a suitable control panel in that studio so as to be readily accessible to the announcer thereat. The main relay MB1 is connected to the studio control equipment CE1 through a channel 23 so that the entire output of studio A may be quickly cut oif. A nemo circuit is also provided in this arrangement or connecting an outside pick-up point with the studio control equipment so that the program ct the pick-up point may be controlled at the studio. The apparatus for studio B is similar to that for studio A ant therefore the description of the apparatus for studio B need not be repeated herein.

Figs. l and 5 show one embodiment of a multiplex broadcasting system to which the principles of this invention have been applied. ln this system' there are. showna plurality or" studios A, B and C, and a plurality orn transmitting stations comprising radio transmitters ST1 to ST4, inclusive, and a plurality of radio antennae TA1 to TA1, inclusive, corresponding, respectively, to radio transmitters ST1 to ST1. These'studios and transmitting stations are interrelated so that the progra is originating at these studios may be simultaneously broadcast by the transmitting stations, the system being so interlocked at no two vstudios may be connected to any one transmitting station at the same time. Each studio has a pluralityv of control relays, one corresponding to each of the transmitting stations. Accordingly, there are four control relays B1 to B1, B1 to R1 and R1 to R1 at the studios A, B and C, respectively. Some of the apparatus for connecting one studio with a particular transmitting station is located at that studio and the rest of the apparatus is located at the control room. Each studio has a program microphone and an announcers microphone. 'Moreover a nemo circuit is connected to each studio so that the program from some distant pick-up point may be brought into the studio in order to be transmitted through an appropriate transmitting station. The program microphones MP1, siPg, MP0, the announcers microphone-s MA1, MA1, MA3, and the nemo circuits NC1, NC2 and Nfl?, correspond, respectively, to studios A, B andC. Switches K and K10, K0 and K10, K0 and K10 are also located at the respective studios so that any one or more of the transmitting stations may be transferred by these switches to one or the other of the studio microphones, or to the microphone at some pick-up point connected to the corresponding nemo circuit. Studios A, B vand C terminate in studio bus bars SB1, SB and SBS, respectively, andthe transmitting stations are connected through line amplifiers LA1 to LA1, inclusive', to corresponding channel bus bars CB1 to CB1, inclusive.

For the sake ot convenience the course of transmission from one of the studios, such -as studio A, to one of the transmitting stations, such as that associated with the channel bus bar CB1, will now be considered in greater detail. A microphone control panel CP1 is located at studio A, this control panel adjoining the program microphone MP1 and the announcers microphone 'MA1. Suitable means are associated with the microphone control panel CP1 for feeding' current from a battery (not shown) 'to either or both of these microphones and other means vare provided for observing the magnitude of the current flowing from the battery through the particular microphone connected to the control panel CP1. lt will be understood that these microphones may be of any well known type, such as, for example, a carbon transne n mitting microphone or a condenser microi phone with its associated amplifier.

rlihe circuits connected to the microphone control panel CP1 have become known as theV program and announcers circuits. These circuits are connected, respectively, to thev lower contacts ,7' and of the switches K0 and K10. that equipment at studios B and C is similar to that at studio A and the description of equipment at studio A applies equally well toV studios B and C. A nemol circuit NC1 is However it will be understood v CTI connected to the contacts a and b of the, switch K9. Switches K9 and K10 are so arranged to connect the 'program microphone MP1, the announcers microphone MA1 or the nemo lcircuit N01 with the input of an ainpliier @A1 at the control room.

Three lamps, L10, L11 and L15 at studio A are also operated by the switches K9 and E15, and indicate to the announcer Whether switches lilo and Km have been operated to connect the program microphone MP1, the announcers microphone. MA1'or the nemo circuit HC1 with the amplifier UA1. rllhis will be described iii greater detail hereinafter. Y

The main transmission path may be tollowed 'from the contacts e and f et the switch K10 through the amplifier @A1 at the control zrooin, which is terminated in a suitable iinpedance l3'l`1, through the inner contacts made by armatures o and c of the relay R5 to the studio bus bar SE1. VThe main relay R5 functions to open the circuit between studio A and the corresponding bus bar S131 at 1 times when it is considered undesirable to transmit that Whichis taking place at lthe studio. A volume indicator LL is bridged across the main transmission path between the output of the amplifier @A1 and the terminating impedance P'l1 to indicate the transmission volume after ampliiication. The value of the impedance P'l1 is low as compared to theimpedance of input of the amplifiers LA1 to LA1, inclusive. rIhus,

when one amplifier, as, for example, the amplifier LA1, is connected to the studio bus bar SE1, other amplifiers, such as LAg, LA3 or LAM, may be connectedthereto, or disconnected therefrom, without appreciably affecting the energy transmitted by the amplifier LA1 This is so becauseiinost of the power trans- V mitted by the amplifier CA1 is being expendvin the input of each to minimize the possibility7 of cross-talk beed in the low impedance P'l`1 and very little line amplifier. ln order tween studio bus bars `or channel bus bars when studio bus bar SE1 is disconnected from the ainplitierCA1, a contact is closed by an armature Z of the main relay R5, which nuts a short circuit across the studio bus bar so that when the main' relay R5 is not energized'tlie line relays LR1 to LEM-inclusive,similarlybecome short-circuited so that these line relays are unable to receive any program, Vthus preventing any g voltages, which may be induced in these circuits, from being impressed upon the input ot any line amplifier. and hence amplified, causing objectionable cross-talk or interference. rThe operation of the line relays LR1 to LR1 will be givenin greater detail in the description hereinafter following. Y

r1lh t 'l'l tthntv tll i e system is so ,aie ou a any s ucio may be connected with one or more transmitting stations simultaneously, and similarly,

the other studios. Vdescribed in greater detail hereinafter.

any transmitting station may be connected withv studio. One of the distinguishing features of the invention `is an interlocking arrangement which `prevents 'any one transmitting station Jfrom being connected to more than one studio at the Vsame time.. rlhis is absolutely essential to prevent confusion between programs, and is an essential eat'ure'of' mitting station. Moreover, line relays LR1 to LR1, Liq to LEM, lili-1 to LR1, associated with the studios A, B and C, respectively, are so arranged as to yprevent any one transmitting station from being connected to more than one studio at the same time. Failure of operation. or improper operation of the relays LRD L31 and LR1 would permit the transmitting station associated with the chai'inel bus bar CB1 to be connected to the studios A, i3 and C, simultaneously. Similar undesirable effects follow the failure of the other line relays. Y

Another feature or" this invention is the provision or a signaling system throughout the studios and the control room to keep the announcers at the various studios and the operator at the control room continuously advised of the manner in which the' studios are connected with the various transmitting stations. lt is another feature of this invention to provide means for the announcer at any Y i at the same time. lllhus, the announcer at any studio has at his disposal apparatus Jfor picking up and releasing the various transmitting stations, and he has also a signaling system which keeps him continuously advised as to whether or not these transmitting stations are already connected to his studio or to .one 'oi rilhese features Ywill be ln studio A the keys K1 and K5, which are momentary contact keys, control the opera'- tion of relay R1. By closing key K1 the relay R1 becomes energized by the Vflow of current through the winding ot said relay from abati tery B1, the circuit including the armature of the relay 1K1, conductor 2l, key K1, the winding of the relay R1, key K5, key K11, conductorV 22, key K1, and ground. As the winding of the relay R1 beconiesenergized its armature A closes a contact c so that the Winding of the relay R1 receives current also from a battery B2, this circuit including key K1?, conductor 23, key K11, the armature A andthe contact c of the relay R1, the Winding or" the relay R1,

key K5, key K11, conductor 22, key K17 and ground. After contact c of the relay R1 has been closed by the armature A of that relay, relay R1 remains energized even after key K1 is released. Shortly after contact c of the relay R1 is closed by armature A, another contact CZ is closed by armature A. Current then flows from the battery B2 through the Winding of the relay TR1, this circuit including the battery B2, the key K17, conductor 23, key K11, the armature A of the relay R1, contacts c and Z of relay R1, conductor 24, the Winding of the relay TR1 and ground. Thus, as the armature A of the relay R1 closes its contact d, the relay TR1 becomes energized so that its armature opens the contact associated therewith, disconnecting battery B1 from the Winding of the relay R1. Yet the Winding of the relay R1 remains energized by the flow of current from the battery B2 through the circuit including key K11, the conductor 23, the key K11, the armature A, the contact c and the Winding of the relay R1, key K5, key K11, cnnductor 22, key K17, and ground. However, current may flow through the keys K1 and K1 in the studios B and C, respectively, only When the relay TR1 is deenergized. After relay R1 has operated to close contact Z and after relay TR1 has become energized, the relays R1 and R1 in the studios B and C cannot become operated by keys K1 and K1 in studios B and C, respectively until the relay TR1 has become deenergized again.

The Winding of the relay LR1 is in parallel relationship With the Winding of the relay R1 through the conductor 25, and therefore the. energization or deenergization of the relay R1 causes a corresponding action of the relay LR1. The armatures a and b of the relay LR1 are connected through the channel bus bar CB1 to the line amplifier LA1, the radio transmitter ST1 and the transmitting antenna TA1. Therefore, when the line relay LR1 and the relay R1 become energized the main transmission circuit between the studio A and the transmitting station associated With the bus bar CB1 becomes closed.v Furthermore the lamp L5 at the studio `indicates to the announcer that the relay R1 hasy operated. Similarly the lamp L19 at the control room indicates to the operator thereat that the line relay LR1 has also operated. The circuit of lamp L11, includes the battery B10, lamp L19, the armature c of the relay LR1 and ground. The relay R1 at studio A may be deenergized by operating key K5, key K11 or key K11, these keys all being included in a series path Which includes the Winding of the relay R1. Keys K11 and K17 are also in series With the Windings of relays R2, R3 and R1, and hence are the studio and control room master release keys, respectively.

In order that the announcer at studio A may know that one or more of the transmitting stations are ready to'receive a program. lamps L1 to L1, inclusive, are provlded.

These are located in the studio, each lamp being associated With one of the transmitting stations, each lamp beingl also associated With one of the relays R1 to R1, inclusive. Lamps L1 to L4 at studio A, lamps L1 to L1 at studio B and lamps L1 to L1 at studio C are controlled by signal keys SK1 to SK1, respectively, which are located in the control room, and Which are under the supervision and control of the operator at the control room. Furthermore, means are provided so that by the operation of one of the relays, such as relay R1 in studio A, the lamps L1 and L1 in studios B and C, corresponding to the relays R1 and R1, respectively, in these studios, Will become extinguished. Thus the light L1 advises the announcer in studio A that the carrier Wave of the transmitting station associated With the channel bus bar CB1 is on the air and that the transmission system to that transmitting station is ready for service from studio A. By operating one of the signal keys such as key SK1, the lamp L15 associated With this key becomes illuminated by the flow of current from battery B5 through the lamp L15, the key SK1 and ground. The lamp L1 also becomes illuminated regardless of the state of energization of the relay R1, as Will beV shown more clearly hereinafter. When the winding of the relay R1 is deenergized current flows from the battery B1 through the armature of the relay TR1, conductor 2l, contact f and armature B of the relay R1, the lamp L1, key SK1 and ground. When the Winding of the relay R1 becomes energized, current then flows from the battery 31 through the key K11, conductor 23, the key K11, contact e and Iarmature B of the relay R1, lamp L1, key SK1 and ground. Similar'- ly the lamps L1 and L1 are operated by the key SK1 With current from battery B1, When the corresponding relays R1 and R1 in studios A and B, are deenergized. Yet when the Winding of the relay R1 in studio A becomes energized the corresponding lamps L1 and L1 in studios B and C, respectively, become extinguished, While lamp L1-in studio Arremains illuminated. This therefore indicates to the announcers instudios B and C that the transmitting station corresponding to the channel bus bar CB1 is not available for transmission from studios B and C. Ob! viously When relay R1 again becomes deenergized, all of the lamps L1, L1 and L1 in the various .studios again become illuminated, therefore indicating that the transmitting station corresponding to the channel bus y Y Y K11 being underl the supervision and control l ,the transmitting stations trom the studio under the control ot a particular announcer.

' The keys K11, K11 and K1, at the control room break the circuits 01": theV batteries B2,

B1 and B1, thereby releasing the relays R1 lto R1, R1 to R1 and R1 to R1 in the studios A, B and C, respectively. The keys K11, K11 and K11 at .the various studios operate in a similar manner. rIhis enables either the announcer in the studio or the operator in the control room to simultaneously release all of the transmitting stations connected to his (the announcers) studio.

The apparatus at the studios A, B and C accomplish primarily the following: first, a suitable arrangement is provided whereby the amplifiers CA1 to CAS, inclusive,at the control room may be connected to the corresponding announcers microphones MA1 to MAg, the program microphones MP1 to MPs or to the microphones at dista-nce points to which the nemo circuits NC1 to NCg, respectively, are connected; second, the announcers at the various studios are equipped to pick up or release any one or more ot the transmitting stations which are connected to the channel bus bars CB1 to CB1, inclusive; third, lamps are provided in the various studios so that the announcers in these studios may know what transmitting stations are available to transmit the program matter; and fourth, lamps are provided throughout the studios and the control room to indicate to the studio announcers and the control room operator whether or not thc relays have properly operated.

In studio A the output ot the announcers microphone MA1 passes through the microphone control equipment CP1 to the lower contacts y' and 7c of the switch K10, Whereas the output ot the program microphone MP1 similarly passes through the' microphone control equipment CP1 to the lower contacts 7' and la of the switch K0. The nemo circuit NC1 is connected to the upper contacts a and b ot the switch K0. The upper contacts a and b of the switch K10 are connected to the blades e and f of the switch K0. The blades e and f of the switch K10 are connected to the input of the amplilier CA1 at the control room. Vhen the switch K10 is thrown downwardly to engage contacts j and 7c, the announcers microphone MA1 is then connected-to the input of the amplifier CA1. By throwing-the switch K10 upwardly to engage contacts a and and switch K0 downwardly to engage contacts y' and 7s, the program microphone MP1 is then connected to the input of the amplifier .CA 1. By throwing! both switches K9 and K10 to the upward positions, the nemo circuit NC1 is then connected to the input ot' the amplifier CA1`. By leaving switch K0 in its upward position, by operating switch K10 theV announcer at studio A may connect the announcers microphone MA1, or the nemo circuit NC1, to the input of the ampliiier CA1.

A lamp L11 is located in studio A and'provides an indication to the announcer at studio A that the equipment of the control room corresponding to studio A is in readiness for operation. It will be understood that this lamp L13 may, if desired, be a colored lamp to distinguish this vlamp trom all the other lamps. By closing key Km, the control room operator sends current from battery B0 through the lamp L11, the circuit including battery B0, keyKN, conductor 27, lamp L13 and ground. Another lamp, L11, which is located at the control room, is alsoV operated byvkey K18. rlhe'lamp L17 similarly indicates to the operator at the control room that the apparatus at the control room corresponding to the studio A is' in readiness for operation. includes thebattery B0,key K18, lamp L1T and ground. It is to be noted that the winding of the main relay R0 can not become energized unless the key K18 in the control room has first operated. This therefore prevents the announcer at studio A from transmitting his program to one or more of the transmiti ting stations beforeV the proper connections have been madein the 'control room. Y

A lamp L0 is located at studio A and provides a visible means ot indication to the announcer at that studio that he is wanted on a telephone intercommunicating system (not'shown). This lamp L0 is operated by key` K16 at the controlroom. By operating key K1G current flows from the battery B1 through key K10, the `conductor 28, lamp L0 and ground.

Relays SR1 to SR1, inclusive, are provided at the control room so that when the corresponding line amplifiers LA1 to LA1 are ready tor use but are not connected to a studio bus bar the inputs ofthese line amplifierswillbeshort-circuited. In other words, when the relays LR1 to LR1, inclusive, are not energized,relays SR1 to SR1, inclusive, will be operated. More Vspeciically the relays SR1 to SR1willbe operated when the line relays corresponding to the various studios are not. energized, these line relays being LR1, LR1 and LR1, LR2, LR2 and LRZ, LRS', LR1, LRS", LR4, L34. and LR1, respectively.

The relays SR1 to SR1 are interlocked with the relays IR1 to 1R1 and the keys SK1 to SK1 so as topermit their-operation, respectively, only when the corresponding keys SK1 to SK1 are operated and whenthe corresponding relays llt-1 to IR1 are unoperated. For thesake of simplicity the operation of only one of the relays, SR1, will be The circuit ot' the lampL17 considered. One terminal of the winding of the relay SR1 is connected to ground through conductor 29 through the middle contact of the key SK1. The other terminal of the winding of the relay SR1 is connected to the battery B1 through conductor 30, conductor 2l and the armature of the relay TR1. Therefore upon the operation of the key SX1 current flows from battery B1 through the winding of the relay SR1, thereby operating said relay. The armature of the relay SR1 is then attracted, providing a short-circuit for the input amplifier LA1. The relay SR1 is always operated to put a short circuit on the input of the amplifier LA1, when the key SK1 is operated, and when, also, the winding of the relay TR1 is not energized. When the winding of the relay TR1 becomes energized, as, for example, when relay R1 in studio A becomes energized, the circuit connecting battery B1 and the winding of the relay SR1 is opened, deenergizing the winding of relay SR1, removing the short-circuit from the input of the amplifier LA1 and placing this channel in an operative condition. Similarly relays SR1, SRc and SR.1 are energized by current from `ba tery B1 through the armatures of relays TR2, IRE, and TR1, the conductors 3l, 32 and 33, the conductors 3A, 35 and 36, the windings of the relays SR2, SR3 and SR1, the conductors 37 38 and 39, the middle contacts of keys SX1, SK3 and SK1, respectively, and ground.

The main relays R0, R0 and R0 open the main transmission paths between studios A,

B and C, and the studio bus bars SB1, SB1

and SB0, respectively, when it is considered undesirable to transmit that which is taking place in these studios. Coniining the description to the apparatus at the control room corresponding to-the studio, A and to that in studio A it is apparent that one terminal of the winding of the relay R0 is grounded and that the other terminal of the winding of the relay R0 is connected through conductor A() to the contacts c and e, of the switch K10. The blade g of the switch K10 is connected to the battery B0through conductor 27 and key X18, when key K18 is closed. Furthermore, when key K10 is closed, the operation of switch K10 to close either of contacts c or c permits current to flow from battery B6 through conductors 2?' and l0 and throughthe winding of the relay R0. When the winding of the relay R0 becomes energized, one of its armatures a closes a contact which permits current to flow from battery B7 through lamp L1 S, the armature a of the relay R0 and around. This lamp indicates to the operator at the control room whether or not the relay R0 has operated. Moreover the `contacts Z) and c of the relay R0 control the main transmission path between the amplifier CA1 and the studio bus bar SB1. When the winding of the relay R6 is not energized the armature' d of said relay short-circuits the studio bus bar SB1, thereby short-circuiting the line ampliliers connected thereto.

Vhen key K10 is operated, causing lamp L13 to be illuminated as an indication to the announcer in studio A that everything in the control room is in readiness for transmission from studio A, and when switches K0 and K10 are operated toconnect the program microphone MP1, the announcers microphone MA1 or the nemo circuit N01, to the input of the amplifier @A1, either lamp L11, L12 or L10 is illuminated to indicate to the announcer' whether the program microphone MP1, the announcers microphone MA1, or the nemo circuit N01, respectively, is connected to the input of the amplifier UA1. The circuit for lamp L11 is as follows: battery B0, key K10, conductor 27, blade 7L and blade d of switch K10, blade g and blade e of switch K0, lamp L11 and ground. The circuit for lamp L12 is as follows: battery B0, key Km, conductor 27, blade 7L and blade m of switch K10, lamp L12 and ground. Similarly the circuit for lamp L10 is as follows: battery B0, key X18, conductor 27, blade h and blade d of switch K10, blade g and blade c of switch K0, lamp L10`and ground.

A relay R5 controls a signal lamp L16 which is a visible indication to the operator at the control room that the announcer at studio A has set up his equipment so as to transmit the program coming over the nemo. circuit NC1. The winding of the relay R5 is connected to a battery B0 through a conductor Al and the blades al and 7L of the switch K0. inasmuch as the switch K0 must be thrown to its upward position to connect the nemo lcircuit N01 tostudio A, the re-.

lay R5 will thereupon become energized, illuminating the lamp L10 by the flow of current therethrough from the battery B8. Similar arrangements are provided in the control room in connection with studios B and C. v

The line relays LR1 to LR1, LR1 to LR1 and LR1 to LR1, inclusive, are so arranged that the input of theampliliers LA1v to LA4, inclusive, may be switched from one studio bus bar, such as SB1 to any one or the other of the studio bus bars, such as SR2 and SBB. This has been explained hereinabove. Yet in each of these line relays, such as, for example, LR1, one terminal of the winding of this relay is connected to the armature c of said relay, both being grounded. The contact with which the armature c engages connects a lamp L19 to a battery B10, thus illuminating lamp L10. This lamp therefore indicates that the relay LR1 has operated. Moreover the armatures a and b of this relay control the transmission path between the studio bus bar SB1 and the ampliiier LA1. The other terminal of the Vwinding of the relay LR1 is connected to the 6@strolling the transmission of the various prowinding of the relay R1 inl studio A. rFliese windings are in parallel relationship with each other and consequently are simultaneously energized or deenergized.

The phrase transmitting station as employed herein designates a radio transmitter, public address equipment, an individually located loud spealreror any other suitable signaling circuit. rlhe word studio as employed herein designates a place where a program of news, music or any other sound originates, whether it be in a room adjacent to thecontrol room or at some point distant from the control room requiring a connection thereto by local or long distance telephone lines or any other suitable signaling medium.

While only three studios and four transmitting stations have been shown and described in Figs. 4f and 5, it will be understood that the system is adaptable to connect any number of studios andany number of transmitting stations within the scope of the invention.

While no auxiliary equipment, such as equalizers, repeating coils, jacks, artificial lines, etc., not absolutely essential to the operation of the system, are shown herein, it is to be understood that they may be added, as they are found desirable, in any manner well known to the art without departing from the spirit o-f the invention or the scope of the appended claims.

While the invention has been disclosed in .certain particular embodiments herein merely for the purpose of illustration, it is to be understood that the general principles of this invention may be applied to other and widely varied organizations without departing from the spirit of the invention and the scope of the appended claims.

What is claimed is: l. In a radio broadcasting system, a plurality of program sources, a plurality of provgram ltransmitting stations, means for connecting the program sources tothe various program transmitting stations so that the programs of said sources may be broadcast thereby, and means whereby not moreV than one program source may be connected to any one program transmitting station at a time.

2. ln a radio broadcasting system, a plurality of sources of program, a plurality of transmitting stations each employing a different carrier Jfrequency, and means for interconnecting the sources of program and the transmitting stations and for preventing two sources of program from being simultaneously transmitted by any one transmitting station.

3. in a radio broadcasting system, a plu` rality of sources of program, a plurality of I transmitting stations each employing a different carrier Jfrequency, and meansfor congrams through the various transmitting stations and for preventing two sources of program from being simultaneously transmitted through any one transmitting station.

4. ln a radio broadcasting system, a plurality of program sources, means for simultaneously broadcasting these programs into space through different transmitting stations, and means for preventing the simultaneous transmission of more than one program through any one transmitting station. f

5. A. system for simultaneously distributing a plurality of programs into space, comprising means for generating a plurality of programs, a plurality of transmitting staions, and means whereby a predetermined number of said transmitting stations may simultaneously transmit each of said programs into space and whereby only one program may be transmitted byeach transmitting station.

6. Asystem for distributing a plurality of programs intospace, comprising means for generating a plurality of programs, a plurality of transmitting stations for simultaneously transmitting these programs into space, and means for preventing the simultaneous transmission of more than one program by any one transmitting station.V

7. in a multiplex broadcasting system, a plurality of program sources, a plurality of transmitting stations, means for interconnecting said program sourcesand said transmitting stations including apparatus to con trol the transmission of'said programs individually through said transmitting stations, and a plurality of indicating devices for each program source one corresponding to each transmitting station to indicate which transmitting stations are available for program transmission. Y

8. In a multiplex broadcasting system, a plurality of studios wherein programs originate, a plurality of transmitting stations, a control room interconnecting said studios and said transmitting stations so as to control v nate'a plurality of transmitting stations, a

plurality of channels of transmission one corresponding to each transmitting station, means for interconnecting said channels of transmission so that the programs' originating in said studios may be simultaneously broadcast by said transmitting stations, and

channels of transmission corresponding to the 130 channels of transmission correspondingto the Vrespective studios to be simultaneously connected to any one of the transmitting stations through the corresponding channel of transmission.

10. The method of multiplex broadcasting, which consists in generating a predetermined number oi` programsy ofV broadcastv matter, generating' a predetermined number of radio frequency waves, controlling the transmission of said programs by said radio frequency waves, preventing the simultaneous transmission of any two programs by any one radio frequency wave, and preventing the transmission of'any one program by any one of the radio frequency waves until the predetermined number of programs and the predetermined number of radio frequency waves are in operating condition.

11. In a multiplex broadcasting system, means for generating a plurality of programs or" broadcast matter, means for generating a plurality of radio frequency waves, means for controlling the transmission of any one program source to a predetermined number of radio frequency waves, and means for preventing the simultaneous transmission of other program sources on the same radio frequency wavesy to which said program source is already connected.

l2. In a radio broadcasting system, a plu- -r rality of program sources, 'a plurality -of transmitting stations, means at said program sources for simultaneously transmitting the programs of said sources through said transmitting stations, means at said program sources for indicating which transmitting stations are available for prcgrain transmission, and means for preventing the simultaneous transmission of they programs from any two or more sources through any one transmitting station.

13. In a radio broadcasting system, a plurality of studios wherein broadcasting programs originate a plurality of transmitting stations, a plurality of groups of relays one group corresponding to each transmittingy station, means for energizing said relays so as to transmit the programs of said studios simultaneously through l said transmitting stations, means whereby only one of the relays corresponding to one of the transmitting stations may be energized at the same time, and means for indicating which transmitting stations are disconnected from the studios and are otherwise available for program transmission.

14. In a radio broadcasting system, the combination of a plurality of program sources, a plurality of radio transmitters vof different frequency characteristics, and means for interconnecting said program sources and said transmitters and for preventing the programs of two sources from being simultaneously transmitted through space by the same transmitter. y

15. In va radio broadcasting system, the combinationv of a plurality of program sources, a plurality of radio transmitters of different frequency characteristics, means for controlling the transmission of said programs by said radio transmitters, said pro- -meaiis whereby any ofthe radio transmitting stations may be connected to, or disconnected from, a program source to which a predetermined number of radio transmitting stations are already connected without appreciably affecting the transmission of program to the radio transmitting stations previously connected thereto.

17. In a radio broadcasting system, a plurality of program sources, a plurality of program transmitting stations, means for connecting the program sources to the Various program transmitting stations so that the programs of said sources may be broadcast thereby, and means whereby any group of program transmitting stations may be simultaneously connected to, or disconnected from any v'program source, so that while said group of program transmitting stations is so connected, no programtransmitting Vstation of said group may be connected to any other program source.

18. In a radio broadcasting system, a plurality of program sources, a plurality of program transmitting stations, means for connecting the program` sources to the various program transmitting stations so that the programs of said sources may be broadcast thereby and for preventing' any two program sources from being connected to the same program transmitting station, and means whereby any group of program transmitting stations may be simultaneously connected to, or disconnected from, any program source so that while said group of program transmitting stations is so connected, a predetermined number of said .group of program transmitting stations may be immediately connected to any other program source.

19. In a radio broadcasting system, a plurality of program sources, a plurality of radio transmitting stations, means forconnecting said program sources to said radio .transmitting stations sothat the programs of said sources may be broadcast-individually by said transmitting stations, and means whereby the electrical characteristics of the connecting apparatus individual to any one radio transmitting station can not substantially affect the program matter transmitted to any other radio transmitting station.

2O. In a radio broadcasting system, a plurality of program sources, a plurality of program transmitting stations, means for connecting the programsources to the various program transmitting Ystations so that the programs of said program sources may be broadcast thereby, means whereby a program from oneot said program sourcesmay be supplemented by a program from any point remote from said program source, means tor preventing the simultaneous transmission by a transmitting station of the program originating at a remote point and any program originating at the program source which is being supplemented, and means whereby'said supplementary program may be transmitted toany predetermined number or said program transmitting'stations associated with said program source without necessarily transmitting it to other similarly associated program transmitting stations.

21. In a radio broadcasting system, a plurality of program sources, a plurality of program transmitting stations each operating on a different wave length, means for connecting the program sources to the various program transmitting stations so that the programs of said sources may be broadcast thereby, means for preventing the programs of two of said sources from being simultaneously broadcast by any one transmittingstation, and means wherebythe volume'transmitted to all ot' said program transmitting stations connected to any one oi said program sources may be simultaneously changed by equal magnitudes.

22. In a'radio broadcasting system, a plurality of program sources, a plurality of program transmitting stations each operating on adiiierent wave length, means for connecting the program sources to the various program transmitting stations so that the programs ot said program sources maybe broadcast thereby, means for preventing the programs oi two or more of said sources from being simultaneously broadcast by any one transmitting station, and means whereby the volume tra-nsmitted to any particular program transmitting station may be suitably controlled wit-hout aecting the volume transmitted to any of the other program transmitting stations connected to the same program source.

23. In a radio broadcasting system, a plurality of program sources, a plurality of program transmitting stations, and means for connecting said program sources to said program transmitting stations so that the programs off said program sources may be broadcast thereby, and means for reserving any pro-gram transmitting station for any program source until said program source is prepared to transmit its program through said program transmitting station and for vpreventing the seizure of said program transmitting station by any other program source.

24. In a radio broadcasting system, a plurality of program sources, a plurality of radio transmitting stations each operating on a ditierent wave length, means for connecting said program sources to' said radio transmitting stations so that the sounds originating at said program sources may be broadcast thereby including means for preventing the simultaneous transmission of sounds originating at any two program sources by any one radio'transmitting station, and means whereby a visual indication may be had at any time of the volume transmitted from anyv one program source to all of the radio transmitting stations associated with said program source.

25. In a multiplex broadcasting system, a

plurality of progra-m sources, a plurality of rality of program sources, a plurality of pro- Y gram transmitting stations, means for connectingl said programrsources to said-program transmitting stations so that the programs of said progra-m sources may be broadcast thereby, and means whereby any voltages which may be set up in the apparatus individual tol one program transmitting station cannot substantially affect the program matter transmitted to any other program transmitting station.

yIn testimony whereof, I have signed my name to this specification this 4th day o August 1926.

EDMUN-D R. TAYLOR. 

